There have so far been presented SCMS (Serial Copy Management System) and CGMS (Copy Generation Management System) as methods for limiting duplication of AV contents for which the copyright has been set, such as music or pictures.
In these systems, it is possible to duplicate contents A1 (first generation), for which the copyright has been set, to acquire (or record) contents A2 (second generation), however, it is not possible to duplicate the contents A2 (second generation) further to acquire contents A3 (third generation), as shown in FIG. 1.